I have a 100A shunt and an opamp, which I'm going to use for measuring current through a battery bank.
But in order to calibrate it, I need to know the actual current flowing through the circuit. I don't have a 100A (or even 50A) capable meter. I could use my 10A-capable multimeter, but I wouldn't be able to measure at the higher current levels.
Can I place a known resistor over a known voltage, and then use Ohm's law to reliably calculate the current?
E.g. if I measure the resistance of a dummy load with a multimeter, and then measure the voltage drop over the resistor, can I then reliably calculate the current?
Also, since my cheap voltmeter can measure up to 10A, I'm thinking to test it with an adjustable power supply, by gradually increasing the voltage until the current reaches maybe 5.00A, and then measure the voltage with a separate voltmeter (so that the circuit remains constant), and then use this to calculate the resistance more accurately.
Is this a stupid way to approach it?